This invention relates to an image recording method and apparatus. For example, the invention relates to control of an optional unit which extends the paper handling function of an image recording apparatus for recording images using an electrophotographic process.
An image recording apparatus such as a laser printer using an electrophotographic process is constructed as shown in FIG. 1. The apparatus has a main body 201 which includes a video controller 202 and an engine controller 203, below.
The video controller 202 mainly is for performing control related to image processing. Specifically, the video controller 202 develops image information into bit data. The image information is sent from an external device (not shown), such as a personal computer, via a general-purpose interface such as a Centronics interface. The engine controller 203 mainly is for controlling corona discharge, exposure, development, transfer, fixing and paper conveyance related to the electrophotographic process. A video interface 204 interconnects the video controller 202 and engine controller 203 to make possible communication between them.
A paper deck option 205 accommodates a large supply of recording paper and supplies the recording paper to the image recording apparatus 201 in response to an instruction from the engine controller 203. A paper deck interface 206 interconnects the engine controller 203 and paper deck option 205 to make possible communication between them.
A sorter option 207 has a plurality of stacking trays for stacking sheets of recording paper, which have been recorded on and discharged from the image recording apparatus 201, while assorting them into prescribed categories in response to an instruction from the engine controller 203. A sorter interface 208 interconnects the engine controller 203 and sorter option 207 to make possible communication between them.
In the arrangement described above, the video controller 202 accepts image information and a print instruction from the external device, whereupon the controller 202 sends the engine controller 203 a video signal, obtained by converting the image information into bit data, as well as the print instruction via the video interface 204. Further, on the basis of a designation made by the user from an operation panel (not shown) connected to the external device or video controller 202, the video controller 202 also transmits a command relating to use of the paper deck option 205 or sorter option 207.
The engine controller 203 controls the components related to the electrophotographic process, namely the components for corona discharge, exposure, development, transfer, fixing and paper conveyance, within the image recording apparatus 201 and carries out image recording on the basis of the received video signal. At the same time, on the basis of a command from the video controller 202, the engine controller 203 controls the paper deck option 205 via the paper deck interface 206 to designate the timing of paper feed, and controls the sorter option via the sorter interface 208 to designate assorting of the sheets of recording paper.
Various problems are encountered in the art described above.
Specifically, the engine controller 203 is connected to the two optional units 205, 207 in a fixed relationship and this combination cannot be changed. Accordingly, in order to realize control of a new optional unit, the engine controller is additionally provided with a control capability other than that for controlling the electrophotographic process. Further, in order to provide higher functionality, it is necessary to improve the capabilities of the engine controller which will control these functions.
Environments in which image recording apparatus are used have become more diverse in recent years and this diversification has been accompanied by a desire for higher functionality of installed optional units and for the ability to use a wide variety of optional units freely in different combinations. However, in order to make it possible to control such a wide variety of optional units in the arrangement described above, it is necessary to improve the capabilities of the engine controller and add on controlled systems. The result is a rise in the cost of the engine controller. This rise in cost is a meaningless price increase for users who do not intend to employ optional units.
Furthermore, in a case where a plurality of optional units are combined, it is necessary to know the order in which each unit is connected. In addition, since the recording paper is conveyed between optional units at high speed, it is required that instructions for control of paper conveyance be sent to the plurality of optional units simultaneously and at high speed.